<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      (function () {
        /*
    startsWith()  字符串是否以什么开头 返回true/false
      */
        let str = 'https://www.baidu.com/';
        console.log(str.startsWith('http')); //输出 true
      })();
    </script>
  </body>
</html>
